Microcystin-LR (MC-LR) is a well-known hepatotoxin; however, increasing evidence suggests that it might induce kidney injury. Grass carp (Ctenopharyngodon idella) is one of the most important farmed species and may be affected by MC-LR releasing into waterbody during cyanobacterial bloom. Here, this present study aimed to explore the nephrotoxicity of grass carp by MC-LR. The grass carp received a single intraperitoneal injection of different doses of MC-LR (0, 25, 75, and 100 μg/kg body weight (BW)), and the kidneys were isolated at 24 and 96 h post-injection (hpi). Histopathological examination revealed kidney lesions, with severe hemorrhage, necrosis of the interstitium, and dilation of Bowman's capsule in the 75 and 100 μg MC-LR/kg BW groups. Under transmission electron microscopy, a larger number of swelling and vacuolated degeneration of mitochondria were observed; moreover, apoptotic features, such as condensed chromatin and shrinkage of cells, were observed in the 75 and 100 μg MC-LR/kg BW groups at 96 hpi. MC-LR significantly upregulated the number of apoptotic cells in the 75 and 100 μg/kg BW groups at 96 hpi as indicated by terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay (P < 0. 05). The results of quantitative assays showed that the mRNA expression of Bax, caspase-9, and caspase-3 in grass carp kidney were significantly increased at 96 hpi in the 75 and 100 μg MC-LR/kg BW groups compared with that in the control group, but Bcl-2 mRNA expression was significantly decreased in all the treatment groups at 24 and 96 hpi. Taken together, these results indicated that MC-LR damaged the kidney structure and resulted in renal apoptosis which may occur via the mitochondrial pathway.

中文翻译：

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MC-LR对草鱼肾脏组织结构和细胞凋亡的影响。

微囊藻毒素-LR（MC-LR）是一种众所周知的肝毒素。但是，越来越多的证据表明它可能引起肾脏损伤。草鱼（Ctenopharyngodon idella）是最重要的养殖品种之一，在蓝细菌开花期间可能受MC-LR释放到水体中的影响。在这里，本研究旨在探讨MC-LR对草鱼的肾毒性。草鱼接受一次腹膜内注射不同剂量的MC-LR（0、25、75和100μg/ kg体重（BW）），并在注射后24和96 h（hpi）分离肾脏。组织病理学检查显示，在75和100μgMC-LR / kg BW组中，肾脏病变，严重出血，间质坏死和Bowman囊扩张。在透射电镜下 观察到大量的线粒体肿胀和空泡变性；此外，在96 hpi时，在75和100μgMC-LR / kg BW组中观察到凋亡特征，例如染色质浓缩和细胞收缩。如末端脱氧核苷酸转移酶（TdT）dUTP缺口末端标记（TUNEL）分析所示，MC-LR在96 hpi时显着上调了75和100μg/ kg BW组的凋亡细胞数（P <0. 05）。定量分析的结果表明，与对照组相比，在75和100μgMC-LR / kg BW组中，在96 hpi时，草鱼肾脏中Bax，caspase-9和caspase-3的mRNA表达显着增加。但是，所有治疗组在24和96 hpi时Bcl-2 mRNA表达均显着降低。在一起